There exist apparatus in the field of traffic:
a speed measurer which with the aid of a Doppler effect captures the instantaneous and precise measurement of speed with the essential aim of its reduction
a measuring traffic station which shows with the aid of electromagnetic loops the average speed of a group of vehicles, the spread, the number of vehicles exceeding a speed threshold.
These materials are highly priced and inconvenient: for the first, FF50,000, and the cost of the case for the second, FF100,000 and the cost of the armour. Moreover, the procedure necessary with the second by the civil engineers costs about FF30,000 to set up for each measurement point.